Controlling Radio Measurements of a User Equipment within a Cellular Network System

ABSTRACT

It is described a method for controlling radio measurements of a user equipment within a cellular network system, wherein the user equipment is served by a cell of a first cell type characteristic, the cell being assigned to a base station, wherein the cellular network system includes the cell and at least one further cell of a second cell type characteristic. The method includes providing, by the base station, a radio measurement configuration to the user equipment, wherein the radio measurement configuration is indicative for parameters to be applied by the user equipment for radio measurements, the radio measurement configuration includes different parameters being assigned to different cell type characteristics, and controlling the radio measurements of the user equipment based on the provided radio measurement configuration.

FIELD OF INVENTION

The present invention relates to the field of cellular networks and inparticular to heterogeneous networks.

ART BACKGROUND

Cellular network systems may be arranged in multi-layer cellularsystems—also referred to as heterogeneous networks (HetNet). In thiscontext, multi-layer refers to cases with a mixture of macro basestations and small power base stations (for instance pico and micro).Macro-layer and pico/micro layer may also be implemented in differentradio access technologies (RAT), for example GSM macro layer and LTEmicro layer.

In such networks, a user equipment (UE) may use a measurementconfiguration. A measurement configuration defines how the UE willexperience its environment and acts as an input to mobility managementin connected mode (connected to a base station for an activecommunication) and autonomously in idle mode (without activecommunication). Typically, the Physical Cell Identity (PCI) is used toidentify a cell for the radio without a need for the UE to read thebroadcasted system information. The PCI of a cell is not necessarily aunique network-wide cell identifier. However, the PCI is normally uniqueon a local scale to avoid collision and/or confusion with neighbouringcells.

In such networks, when the UE is moving, there may be the case wheremobility problems for fast moving users are associated with out-boundhandovers from small power cell, e.g. handout from pico cell to anotherpico or macro layer. In the connected mode, the triggering of ameasurement report is controlled by a parameter, called TimeToTrigger(TTT), which is the same regardless of the target cell type. In idlemode, triggering a measurement for cell ranking is controlled with twobroadcasted parameters, t-Reselection and Qhyst. When the UE is campingin a cell, these parameters may be the same during the measurements,regardless of the target cell type while measuring. Due to genericparameter settings, mobility problems may arise when a handover or acell reselection is not performed towards the most suitable cell typebecause the target cell type is not taken into account.

Common measurement configuration setting is not fast enough toreconfigure measurements according to target cell types and thesignalling load would not be feasible in heterogeneous network withdense small cells deployments. Also the support for measurement objectsis limited where E-UTRAN configures only a single measurement object fora given frequency, i.e. it is not possible to configure two or moremeasurement objects for the same frequency with different associatedparameters. This means that measurement configuration support fordifferent cell types without reconfigurations is not possible.

The measurement configuration may have some flexibility only for fastmoving UEs, which can use Mobility State Estimation (MSE) and relatedmobility parameters scaling. MSE scales down mobility parameters basedon the estimated UE velocity and may make fast moving UEs to enter andleave small cells faster. Unfortunately, having UEs connected to smallcells at high velocity is quite opposite to what is desired as thetarget is to improve mobility robustness and one conclusion is to keepfast moving UEs out of small cells.

There may be a need for an improved system and method being adapted toprovide flexible radio measurements.

SUMMARY OF THE INVENTION

This need may be met by the subject matter according to the independentclaims. Advantageous embodiments of the present invention are describedby the dependent claims.

According to a first aspect of the invention there is provided a methodfor controlling radio measurements of a user equipment within a cellularnetwork system, wherein the user equipment is served by a cell of afirst cell type characteristic, the cell being assigned to a basestation, wherein the cellular network system comprises the cell and atleast one further cell of a second cell type characteristic. The methodcomprises providing, by the base station, a radio measurementconfiguration to the user equipment, wherein the radio measurementconfiguration is indicative for parameters to be applied by the userequipment for radio measurements, the radio measurement configurationcomprising different parameters being assigned to different cell typecharacteristics, and controlling the radio measurements of the userequipment based on the provided radio measurement configuration.

This aspect of the invention is based on the idea to improve theflexibility of radio measurements by taking into account the target celltype characteristic. “Target cell” in this context may refer to thecell, for which the measurements should be carried out. The target cellmay also be the target for a following handover. The target cell mayalso be the cell the user equipment is already connected to, i.e. the“serving cell”. The radio measurement configuration may take intoaccount, for choosing the parameters, the serving cell, the target cellor both.

Common systems, for instance E-UTRAN, provide the measurementconfiguration applicable for a user equipment (UE) in RRC_CONNECTED bymeans of dedicated signalling, i.e. using theRRCConnectionReconfiguration message. E-UTRAN only configures a singlemeasurement object for a given frequency, i.e. it is not possible toconfigure two or more measurement objects for the same frequency withdifferent associated parameters, e.g. different offsets and/orblacklists. Measurement object may refer for instance to a specificcell.

The UE maintains a single measurement object list, a single reportingconfiguration list, and a single measurement identities list. Themeasurement object list includes measurement objects, which arespecified per RAT type, possibly including an intra-frequency object(i.e. the object corresponding to the serving frequency),inter-frequency object(s) and inter-RAT objects.

However, the common systems may provide some disadvantages. Consideringthe intra-frequency case, when the UE performs measurements towardsdifferent cell types, only one measurement configuration is possible.Therefore measurements are limited and not providing flexibility towardsdifferent cell types in various heterogeneous network deployments. It isnot possible to configure more than one mobility related measurementparameter (for instance TTT, t-Reselection, Qhyst) value per measurementobject. The Mobility State Estimation can scale down for example the TTTvalue in RRC connected mode by factors [0.25, 0.50, 0.75, 1.00], whichcan make the fast moving UEs to enter small power cells even faster.However, as already explained above, this is not desired.Non-stationary, irregular and/or unpredictable trajectory of users canincrease the need for diverse measurement configurations. When only onemeasurement object is possible for a given frequency, it means that inorder to support mobility through a heterogeneous network area, severalmeasurement configurations or reconfigurations needs to be signalled toUE for optimum mobility performance.

The idea of the herein described method is to enhance the measurementconfiguration and related measurements. The method provides aflexibility to the measurements and can enable support for advancedmobility scenarios especially in areas where heterogeneous networks aredeployed.

According to the described method, when camping on a cell or beingconnected to a cell, the UE may use the enhanced measurementconfiguration to support measurements of different target cell typeswith dedicated parameters in connected and idle mode. The measurementconfiguration may contain a set of dedicated parameters for eachdifferent cell type characteristic. Thus, radio measurements towardsdifferent target cells of different target cell type characteristics canbe done without a measurement reconfiguration process by network.

The described method relates in particular to LTE rel. 11+ and inparticular to HetNet measurements, but is not limited to theseenvironments. The described method provides a way to enhance themeasurement configuration and related measurements so that differenttarget cell types can be supported with optimized measurement parametersimproving the mobility in HetNets. The basic idea is that a UE will beprovided with different measurement configuration for different celltypes (or at least one for macro cell and another one for small cells).

The term “base station” in this context may denote any kind of physicalentity being able to hold one or more cells. A base station in thiscontext may be any kind of network device providing the requiredfunctionality for the method; it may also be a transceiver node incommunication with a centralized entity. The base station may be forexample an eNodeB or eNB.

The term first and second “cell type characteristics” may refer to cellcharacteristics or properties, wherein the first and the second celltype characteristic may be equal or different.

According to a further embodiment of the invention, controlling theradio measurements comprises configuring the user equipment to applyparameters for radio measurements based on a respective cell typecharacteristic.

According to this embodiment, after receiving the radio measurementconfiguration, the UE may be configured in such a way to apply specificparameters for specific radio measurements for specific cell typecharacteristics. With one radio measurement configuration, the UE may beconfigured to apply different kind of measurements (i.e., usingdifferent parameters), for different cell type characteristics. This mayprovide a greater flexibility without a need of a completereconfiguration.

According to a further embodiment of the invention, the method furthercomprises receiving, by the base station, radio measurements from theuser equipment, wherein the radio measurements are based on the providedradio measurement configuration, and scheduling a handover operation ofthe user equipment from the cell to the further cell based on thetransmitted radio measurements.

According to this embodiment, a handover operation may be scheduledbased on radio measurements, which have been carried out based onspecific parameters for specific cell type characteristics. Thus, anefficient handover may be realized as the radio measurements areadjusted based on the cell type characteristics. Further, the UE mayalso take into account which cell type characteristic may be preferredfor a handover.

According to a further embodiment of the invention, the radiomeasurement configuration comprises a table having the cell typecharacteristics and the assigned parameters.

Such a radio measurement configuration table may comprise informationabout neighbouring cell PCIs (physical cell identity) to be measured andcell type characteristics associated to the PCI respectively. The tablemay also comprise a set of dedicated mobility parameters for eachdifferent cell type characteristic. Preferably, a minimum of two sets ofdedicated parameters are given, e.g. parameters for the current/coveragecell (e.g. macro) and for the cell type characteristic relativelysmaller than coverage cell (e.g. pico). The dedicated set of mobilityparameters can comprise of, but is not limited to, TimeToTrigger (forconnected mode), t-Reselection (for idle mode) or Qhyst (for idle mode).

According to a further embodiment of the invention, the cell typecharacteristics comprise at least one of the group consisting of celltype, cell coverage, cell capacity, cell size, cell weight and cellpriority.

The cell type may be defined for instance by macro, micro, pico, femto.The cell coverage may define for instance a region (vertical orhorizontal), in which a connection via the cell may be provided for aUE. The cell capacity may define the amount of communications (formultiple UEs, per UE) which may be supported. Cell capacity and cellcoverage may also be combined under the term cell deployment. The cellsize may define the size of a cell for instance via an enumerated value(e.g., large, medium, small, very small, etc.) or via a numericalabsolute value (for instance diameter or perimeter, which may bespecified in meter or centimeter). The different cells may also beweighted, for instance via a numerical relative value (e.g., 1.5, 1.0,0.5, 0.25; i.e., the larger the weight, the higher the priority or viceversa). Such a weight may be specified for instance during the networkdesign. The cell priority may refer to a priority cell status which maybe assigned to some cells. This may denote that a cell with a higherpriority may be preferred or prioritized over other cells. This may beindependent of the size or other properties of the cells.

According to a further embodiment of the invention, the parameters areindicative for the measurement behavior and/or the reporting behavior ofthe user equipment.

The UE measurement and reporting behavior may be different for thedifferent cell type characteristics of the cells (i.e., may vary fromcell to cell) that the UE measures (or at least for the macro and smallcells) because parameters controlling measurement reporting may bedifferent for macro and small cells (or different cell types). Theparameters may indicate for instance time points for measurements or themanner of the measurements.

According to a further embodiment of the invention, the radiomeasurement configuration comprises a list comprising information of theat least one further cell and the associated cell type characteristic.

Before carrying out radio measurements, the UE should choose theappropriate radio measurement configuration based on the provided radiomeasurement configuration. According to this embodiment, the UE has apre-knowledge about the cell type characteristic of the at least onefurther cell and can thus choose the appropriate correspondingparameters.

In another embodiment, the UE may receive an information signal from theat least one further cell comprising information about the cell typecharacteristic before starting radio measurements.

According to a further embodiment of the invention, the list comprisesinformation about a plurality of neighboring cells and the respectiveassociated cell type characteristic.

The UE may have a pre-knowledge about all neighboring cells, includingthe at least one further cell, based on a neighbour cell list along withcell type characteristics of those cells. This may allow better controlof when and how often radio measurements are reported for different typeof cells which in turn may allow control of when the UE is handover to atarget cell of a specific cell type. This in essence may allow avoidinghigh speed UEs in small cells which might be important for Hetnetdeployment involving macro and small cells.

According to a further embodiment of the invention, controlling theradio measurements of the user equipment is based on the list and theparameters.

The UE may choose the parameters based on the list. Thus, the UE choosea target cell, determines the cell type characteristic of this targetcell based on the list and chooses then the respective parameters.

According to a further embodiment of the invention, controlling theradio measurements of the user equipment is based on the provided radiomeasurement configuration and a classification state of the userequipment.

The UE may take also into account its own classification state whenstarting radio measurements. This may further improve the flexibilityand accuracy of radio measurements.

According to a further embodiment of the invention, the classificationsstate of the user equipment corresponds to a mobility state and isdetermined by applying mobility state estimation (MSE).

According to the specified MSE, but not limited to it, two parametersare scaled according to the mobility state (Q_hyst and T_reselection) inidle mode and one parameter (Time-To-Trigger (TTT)) in connected mode.According to 3GPP Release 8, each UE mobility state has its ownSpeedStateScaleFactors [0.0, 0.25, 0.75, 1.00], where “1.00” is assumedto equal for “normal mobility state”. Scaling factors are applied to thedefined parameters whenever the mobility state of the UE changes. Alsoany other method providing the mobility state or estimate of the mobileactivity may be supported.

It should be noted that the “mobility state”, for instance a highmobility state, of the UE refers to an illustrative description of theUE mobility behaviour and activity. It may refer for instance to theamount of handovers per time. The mobility state in this context shouldbe distinguished from Release 8 mobility states.

For instance, according to this embodiment, if the UE is classified tohigh mobility state, the serving cell is characterized as “small” andthe target cell (for instance the at least one further cell) to bemeasured is characterized as “large”, then the UE may apply the set ofparameter values which are specific for a large target cell type at highmobility state. If the UE is classified to high mobility state, theserving cell is characterized as “large” and the target cell to bemeasured is characterized as “small”, then the UE may apply the set ofparameter values which are specific for a small target cell type at highmobility state. In general, the selected parameter value may depend onboth the serving and target cell types.

According to a second aspect of the invention, there is provided a basestation for cont rolling radio measurements of a user equipment within acellular network system, wherein the user equipment is served by a cellof a first cell type characteristic, the cell being assigned to the basestation, wherein the cellular network system comprises the cell and atleast one further cell of a second cell type characteristic. The basestation comprises a transmitting unit being adapted to provide a radiomeasurement configuration to the user equipment, wherein the radiomeasurement configuration is indicative for parameters to be applied bythe user equipment for radio measurements, the radio measurementconfiguration comprising different parameters being assigned todifferent cell type characteristics, and a control unit for controllingthe radio measurements of the user equipment based on the provided radiomeasurement configuration.

The base station may be any type of access point or point of attachment,which is capable of providing a wireless access to a cellular networksystem. Thereby, the wireless access may be provided for a userequipment or for any other network element, which is capable ofcommunicating in a wireless manner. The base station may be an eNodeB,eNB, home NodeB or HNB, or any other kind of access point.

The base station may comprise a receiving unit, for example a receiveras known by a skilled person. The base station may also comprise atransmitting or sending unit, for example a transmitter. The receiverand the transmitter may be implemented as one single unit, for exampleas a transceiver. The transceiver or the receiving unit and the sendingunit may be adapted to communicate with the user equipment via anantenna.

The control unit may be implemented as a single unit or may beimplemented for example as part of a standard control unit, like a CPUor a microcontroller.

According to a third aspect of the invention, there is provided a userequipment being adapted to communicate with a base station as describedabove and being adapted to carry out radio measurements based on theprovided radio measurement configuration.

The user equipment (UE) may be any type of communication end device,which is capable of connecting with the described base station. The UEmay be in particular a cellular mobile phone, a Personal DigitalAssistant (PDA), a notebook computer, a printer and/or any other movablecommunication device.

The user equipment may comprise a receiving unit or receiver which isadapted for receiving signals from the base station. The user equipmentmay comprise a transmitting unit for transmitting signals. Thetransmitting unit may be a transmitter as known by a skilled person. Thereceiver and the transmitting unit may be implemented as one singleunit, for example as a transceiver. The transceiver or the receiver andthe transmitting unit may be adapted to communicate with the basestation via an antenna.

The user equipment may comprise a configuration unit for configuring theradio measurements based on the radio measurement configuration receivedfrom the base station. Such a configuration unit may be adapted toconfigure the user equipment to perform or carry out measurements basedon the provided radio measurement configuration, taking into account theparameters and the different cell type characteristics. Theconfiguration unit of the user equipment may be implemented for exampleas part of a control unit, like a CPU or a microcontroller. Theconfiguration unit and the transceiver may be coupled or may beimplemented as one single unit.

According to a fourth aspect of the invention, there is provided acellular network system. The cellular network system comprises a basestation as described above.

Generally herein, the method and embodiments of the method according tothe first aspect may include performing one or more functions describedwith regard to the second, third or fourth aspect or an embodimentthereof. Vice versa, the base station, the user equipment or thecellular network system and embodiments thereof according to the second,third and fourth aspect may include units or devices for performing oneor more functions described with regard to the first aspect or anembodiment thereof.

According to a fifth aspect of the herein disclosed subject-matter, acomputer program for controlling radio measurements of a user equipmentis provided, the computer program being adapted for, when executed by adata processor assembly, controlling the method as set forth in thefirst aspect or an embodiment thereof.

As used herein, reference to a computer program is intended to beequivalent to a reference to a program element and/or a computerreadable medium containing instructions for controlling a computersystem to coordinate the performance of the above described method.

The computer program may be implemented as computer readable instructioncode by use of any suitable programming language, such as, for example,JAVA, C++, and may be stored on a computer-readable medium (removabledisk, volatile or non-volatile memory, embedded memory/processor, etc.).The instruction code is operable to program a computer or any otherprogrammable device to carry out the intended functions. The computerprogram may be available from a network, such as the World Wide Web,from which it may be downloaded.

The herein disclosed subject matter may be realized by means of acomputer program respectively software. However, the herein disclosedsubject matter may also be realized by means of one or more specificelectronic circuits respectively hardware. Furthermore, the hereindisclosed subject matter may also be realized in a hybrid form, i.e. ina combination of software modules and hardware modules.

In the above there have been described and in the following there willbe described exemplary embodiments of the subject matter disclosedherein with reference to a cellular network system, a base station, auser equipment and a method of controlling radio measurements of a userequipment. It has to be pointed out that of course any combination offeatures relating to different aspects of the herein disclosed subjectmatter is also possible. In particular, some embodiments have beendescribed with reference to apparatus type embodiments whereas otherembodiments have been described with reference to method typeembodiments. However, a person skilled in the art will gather from theabove and the following description that, unless otherwise notified, inaddition to any combination of features belonging to one aspect also anycombination between features relating to different aspects orembodiments, for example even between features of the apparatus typeembodiments and features of the method type embodiments is considered tobe disclosed with this application.

The aspects and embodiments defined above and further aspects andembodiments of the present invention are apparent from the examples tobe described hereinafter and are explained with reference to thedrawings, but to which the invention is not limited.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a cellular network system according to an exemplaryembodiment of the present invention.

FIG. 2 shows a measurement configuration structure according to anexemplary embodiment of the present invention.

FIG. 3 shows a measurement configuration structure according to afurther exemplary embodiment of the present invention.

FIG. 4 shows a cellular network system according to a further exemplaryembodiment of the present invention.

FIG. 5 shows a graph illustrating a reference signal received power ofFIG. 4.

FIG. 6 shows a cellular network system according to a further exemplaryembodiment of the present invention.

FIG. 7 shows a graph illustrating a reference signal received power ofFIG. 6.

FIG. 8 shows a base station and a user equipment within a cellularnetwork system according to an exemplary embodiment of the invention.

It is noted that in different figures, similar or identical elements areprovided with the same reference signs.

DETAILED DESCRIPTION

In the following, embodiments of the herein disclosed subject matter areillustrated with reference to the drawings and reference to aspects ofcurrent standards, such as LTE. However, such reference to currentstandards is only exemplary and should not be considered as limiting thescope of the claims.

FIG. 1 shows a cellular network system 100. A user equipment 104 isserved by and located in a cell 101. The cell 101 has a first cell typecharacteristic. The cell 101 is served by a (serving) base station 103.The cell 101 may also be called “source cell”. The cellular networksystem comprises at least one further cell 102. The at least one furthercell 102 has a second cell type characteristic. The at least one furthercell 102 is neighbored to the cell 101 and may be the target cell for ahandover. The base station 103 provides a radio measurementconfiguration to the user equipment 104. The radio measurementconfiguration is indicative for parameters to be applied by the userequipment (UE) for radio measurements within the cellular networksystem, for instance for the target cell 102. The radio measurementconfiguration comprises different parameters being assigned to differentcell type characteristics. This means that the UE may choose differentparameters for different cells. The radio measurements of the userequipment are controlled based on the provided radio measurementconfiguration.

In the following, some possible implementations will be described. Itshould be noted that these implementations refer to a connected mode ofthe user equipment (i.e., a mode wherein a communication is establishedbetween the user equipment and the base station). Thus, theimplementation example deals with setting of the TimeToTrigger, themobility parameter that has some importance in mobility performance inconnected mode, since it is the one delaying the handover process.

It should be noted that the herein described method and the problemsolved are also applicable to enhance idle mode measurementconfiguration assuming that the network provides the relevant targetcell specific information via broadcasted system information blocks orvia user equipment specific information as part of the RRC procedures,for instance when the UE mode changes.

Common measurements in LTE may consist of following information elements(IE). The IE MeasConfig specifies measurements to be performed by theUE, and covers intra-frequency, inter-frequency and inter-RAT mobilityas well as configuration of measurement gaps. The IE MeasId is used toidentify a measurement configuration, i.e., linking of a measurementobject and a reporting configuration. The IE MeasObjectEUTRA specifiesinformation applicable for intra-frequency or inter-frequency E-UTRAcells. The IE MeasResults covers measured results for intra-frequency,inter-frequency and inter-RAT mobility. The IE ReportConfigEUTRAspecifies criteria for triggering of an E-UTRA (or EUTRAN) measurementreporting event.

FIG. 2 shows an example of the measurement configuration and FIG. 3shows one way of enhancing the existing measurement configuration.

Such a radio measurement configuration comprises a plurality ofmeasurement objects 201, for instance frequencies, with an associatedobject ID 202. A measurement ID 203 and a report ID 204 are associatedwith each object ID. Further, the report ID is associated with a reportconfiguration ID. The measurement ID 203, the report ID 204 and thereport configuration ID 205 correspond to parameters to be applied bythe UE for any radio measurement.

FIG. 3 has another set of mobility parameters associated to the samefrequency 301 and only the most suitable cell measurement will bereported, in this case associated to event A1 305 as an example.

One way to implement the described measurement configuration is to addfields to IE elements and keep the existing measurement configurationstructure, as shown in FIG. 1. Enhanced measurement configuration mayconsider the relevant information elements related to measurements. Atminimum (but not limited to) IE MeasConfig may contain information aboutthe PCIs, which are associated to cell type characteristics, and IEReportConfigEUTRA may contain the dedicated measurement parameters foreach cell type characteristic, e.g. different TTT for each target celltype characteristic in connected mode. Respectively, the enhancedmeasurement configuration may be extended for idle mode with a list ofPCIs associated with cell type characteristics and t-Reselection andQhyst for different cell type characteristic categories respectively.

Prior to measuring the neighbouring target cells, the UE may adjust itsmobility related measurement parameters based on the target cell typecharacteristics.

Target of the described measurement configuration is to supportmeasurement of several target cells each having their owncharacteristics (capacity, coverage, small, large, macro, pico, . . . ),which may require several TTTs, e.g. at maximum there should be as manyTTTs as there are neighbouring cells of different cell typecharacteristics indicated in the measurement configuration. At minimum,two sets of dedicated parameters are given, e.g. parameters for thecoverage cell (e.g. macro) and for the cells relatively smaller thancoverage cell (e.g. pico).

Another implementation can also use associations of multiple TTT valuesto the measurement configuration. For example two TTT values can be usedwhere fast moving UEs are using long TTT value when measuring towards asmall cell (known from the small cell type associated with a certainPCI), and otherwise using a short TTT value. This may provide theadvantage that a UE can use two measurement configurations without aneed for the network to reconfigure the mobility related measurementsand optionally also without MSE scaling. This is advantageous asreconfiguration takes time and requires additional signalling.

If more than the allowed number of neighbouring cells is measured, onlythe measurements corresponding to the neighbouring cells with the largerreceived signal strength may be reported. Therefore the existingreporting configuration can be supported. The reporting configurationcan be also extended so that the measured cell type characteristic isreported.

The serving cell may periodically broadcast the neighbouring list ofPCIs and associated cell type characteristics. After receiving thislist, the UE may periodically perform the appropriate measurements,where the measurements are using the target cell type characteristicspecific parameters. In connected mode, the UE can be also provided witha specific measurement configuration, indicating which target cells itshould measure. In connected mode, the UE may report back the results tothe serving cell, optionally using the target cell specific measurementconfiguration.

The described method and system is targeted to complex mobilityprocedures where signalling and power consumption at UEs might need tobe minimized. Without the described method and system, UEs need to readtarget cell system information blocks of every neighbouring cell toidentify the target cell type (characteristic) and this may lead todraining the battery and requiring unfeasible amount of signalling toapply the optimum mobility related measurement parameters.

According to the herein described method and system, in connected mode,the UE may select the set of mobility parameters (TTT) according totarget cell type characteristics, and may optionally consider themobility state, and perform instructed measurements. Benefit may be thatfor example fast moving UE will not report cells which are not suitable,e.g. cells classified as small power cells. Furthermore, pedestrianusers will also be supported with the same measurement configurationstructure, and small power cells can be promoted over large macro cellswith a hysteresis offset from the parameter set.

Currently, according to Release-8, the UE does not know if the servingcell or the target cell to be measured is a macro cell or a small powercell, and therefore TTT scaling is only making UEs to enter small cellsfaster. By associating “large cell” type information to macro cells andthen applying suitable set of measurement parameters for mobility, themeasurement may be done using correct TTT, compared to parameter scalingusing MSE. MSE is rather an inaccurate method and does not provideflexible support for heterogeneous deployment.

Such a scenario is shown in FIG. 4. FIG. 4 shows a cellular networksystem 400 with a macro cell 401 and two smaller cells 410 and 420. Thecorresponding RSRP graph is shown in FIG. 5. FIG. 4 illustrates anexample scenario where the serving cell and target cells arecharacterized as “large” and “small depending on the UE trajectory”. TheUE may apply the set of parameter values which are specific for servingcell and target cell, and optionally consider the mobility state. Inthis case, the network can adapt and/or optimize its mobility andrelated measurement parameters (for example using SelfOrganising Network(SON) principles) either to fast moving or slowly moving users, but notfor both. Therefore, measurement flexibility at the UE side by using twoor more sets of measurement parameters will solve the problem of diverseuser mobility profiles at a given geographical area.

FIG. 6 shows an example scenario of a cellular network system 600, wherea “smaller than macro” cell 603 fills a coverage hole between two macrocells 601, 602. In this case, a small cell can be “promoted” formobility purposes by classifying it as “large” cell and then the UEwould apply an optimum set of mobility measurement parameters without aneed for additional RRC signalling or reading target cell systeminformation blocks. Optionally the mobility state can be considered inselecting the set of mobility parameters. The corresponding RSRP graphis shown in FIG. 7.

For in-stationary and irregularly moving users the minimum of two setsof mobility measurement parameters may solve the problem related todiverse user mobility profiles and that parameters do not need to be acompromise between slowly moving and fast moving user profile. Forexample, for fast moving UEs, the target cell type characteristics andtwo sets of measurement report triggering parameters can provide asolution where the most suitable but non-best ranking cells becomefeasible.

The serving cell can collect information about its neighbours using X2or S1 interface and communicate the neighbour cell list with cell typecharacteristics to the UE for example with each handoff, or the sourcecell can broadcast the information to all UEs in SIB, such that a fastUE excludes the measurement and reporting of small cells. This decreasesradio link failure and handover failure probability, increases cellreselection likelihood to more suitable cells and improves UE batterylife.

FIG. 8 shows a cellular network system 800 according to an exemplaryembodiment of the invention. The cellular network system comprises abase station 103 and a user equipment 104 being served by the basestation in a cell.

The base station may be any type of access point or point of attachment,which is capable of providing a wireless access to a cellular networksystem. Thereby, the wireless access may be provided for the userequipment or for any other network element, which is capable ofcommunicating in a wireless manner. The base station may be an eNodeB,eNB, home NodeB or HNB, or any other kind of access point.

The base station may comprise a receiving unit, for example a receiveras known by a skilled person. The base station may also comprise atransmitting or sending unit, for example a transmitter. The receiverand the transmitter may be implemented as one single unit, for exampleas a transceiver 801. The transceiver or the receiving unit and thesending unit may be adapted to communicate with the user equipment viaan antenna.

The transmitting unit or the transceiver 801 are adapted to provide aradio measurement configuration to the user equipment 104, wherein theradio measurement configuration is indicative for parameters to beapplied by the user equipment for radio measurements. The radiomeasurement configuration comprises different parameters being assignedto different cell type characteristics.

The base station further comprises a control unit 802 for controllingthe radio measurements of the user equipment based on the provided radiomeasurement configuration. The control unit may be implemented as asingle unit or may be implemented for example as part of a standardcontrol unit, like a CPU or a microcontroller.

The user equipment (UE) may be any type of communication end device,which is capable of connecting with the described base station. The UEmay be in particular a cellular mobile phone, a Personal DigitalAssistant (PDA), a notebook computer, a printer and/or any other movablecommunication device.

The user equipment may comprise a receiving unit or receiver which isadapted for receiving signals from the base station. The user equipmentmay comprise a transmitting unit for transmitting signals. Thetransmitting unit may be a transmitter as known by a skilled person. Thereceiver and the transmitting unit may be implemented as one singleunit, for example as a transceiver 803. The transceiver or the receiverand the transmitting unit may be adapted to communicate with the basestation via an antenna.

The user equipment may comprise a configuration unit 804 for configuringthe radio measurements based on the radio measurement configurationreceived from the base station. The configuration unit of the userequipment may be implemented for example as part of a control unit, likea CPU or a microcontroller. The configuration unit and the transceivermay be coupled or may be implemented as one single unit.

Having regard to the subject matter disclosed herein, it should bementioned that, although some embodiments refer to a “base station”,“eNB”, etc., it should be understood that each of these references isconsidered to implicitly disclose a respective reference to the generalterm “network component” or, in still other embodiments, to the term“network access node”. Also other terms which relate to specificstandards or specific communication techniques are considered toimplicitly disclose the respective general term with the desiredfunctionality.

It should further be noted that a base station as disclosed herein isnot limited to dedicated entities as described in some embodiments.Rather, the herein disclosed subject matter may be implemented invarious ways in various locations in the communication network whilestill providing the desired functionality.

According to embodiments of the invention, any suitable entity (e.g.components, units and devices) disclosed herein, e.g. the control unit,are at least in part provided in the form of respective computerprograms which enable a processor device to provide the functionality ofthe respective entities as disclosed herein. According to otherembodiments, any suitable entity disclosed herein may be provided inhardware. According to other—hybrid—embodiments, some entities may beprovided in software while other entities are provided in hardware.

It should be noted that any entity disclosed herein (e.g. components,units and devices) are not limited to a dedicated entity as described insome embodiments. Rather, the herein disclosed subject matter may beimplemented in various ways and with various granularities on devicelevel while still providing the desired functionality. Further, itshould be noted that according to embodiments a separate entity (e.g. asoftware module, a hardware module or a hybrid module) may be providedfor each of the functions disclosed herein. According to otherembodiments, an entity (e.g. a software module, a hardware module or ahybrid module (combined software/hardware module)) is configured forproviding two or more functions as disclosed herein.

It should be noted that the term “comprising” does not exclude otherelements or steps. It may also be possible in further refinements of theinvention to combine features from different embodiments describedherein above. It should also be noted that reference signs in the claimsshould not be construed as limiting the scope of the claims.

LIST OF REFERENCE SIGNS

100 Cellular network system

101 Cell

102 Further cell

103 Base station

104 User equipment

201 Measurement object

202 Object ID

203 Measurement ID

204 Report ID

205 Report Configuration ID

301 Measurement object

305 Report Configuration ID

400 Cellular network system

401 Macro cell

410 Smaller cell

420 Smaller cell

600 Cellular network system

601 Macro cell

602 Macro cell

603 Smaller cell

800 Cellular network system

801 Transceiver of base station

802 Control unit of base station

803 Transceiver of user equipment

804 Configuration unit of user equipment

1. A method for controlling radio measurements of a user equipmentwithin a cellular network system, wherein the user equipment is servedby a cell of a first cell type characteristic, the cell being assignedto a base station, wherein the cellular network system comprises thecell and at least one further cell of a second cell type characteristic,the method comprising providing, by the base station, a radiomeasurement configuration to the user equipment, wherein the radiomeasurement configuration is indicative for parameters to be applied bythe user equipment for radio measurements, the radio measurementconfiguration comprising different parameters being assigned todifferent cell type characteristics, and controlling the radiomeasurements of the user equipment based on the provided radiomeasurement configuration.
 2. The method as set forth in claim 1,wherein controlling the radio measurements comprises configuring theuser equipment to apply parameters for radio measurements based on arespective cell type characteristic.
 3. The method as set forth in claim1, further comprising receiving, by the base station, radio measurementsfrom the user equipment, wherein the radio measurements are based on theprovided radio measurement configuration, and scheduling a handoveroperation of the user equipment from the cell to the further cell basedon the transmitted radio measurements.
 4. The method as set forth inclaim 1, wherein the radio measurement configuration comprises a tablehaving the cell type characteristics and the assigned parameters.
 5. Themethod as set forth in claim 1, wherein the cell type characteristicscomprise at least one of the group consisting of cell type, cellcoverage, cell capacity, cell size, cell weight, and cell priority. 6.The method as set forth in claim 1, wherein the parameters areindicative for the measurement behavior and/or the reporting behavior ofthe user equipment.
 7. The method as set forth in claim 1, wherein theradio measurement configuration comprises a list comprising informationof the at least one further cell and the associated cell typecharacteristic.
 8. The method as set forth in claim 7, wherein the listcomprises information about a plurality of neighboring cells and therespective associated cell type characteristic.
 9. The method as setforth in claim 7, wherein controlling the radio measurements of the userequipment is based on the list and the parameters.
 10. The method as setforth in claim 1, wherein controlling the radio measurements of the userequipment is based on the provided radio measurement configuration and aclassification state of the user equipment.
 11. The method as set forthin claim 10, wherein the classifications state of the user equipmentcorresponds to a mobility state and is determined by applying mobilitystate estimation.
 12. A base station for controlling radio measurementsof a user equipment within a cellular network system, wherein the userequipment is served by a cell of a first cell type characteristic, thecell being assigned to the base station, wherein the cellular networksystem comprises the cell and at least one further cell of a second celltype characteristic, the base station comprising a transmitting unitbeing adapted to provide a radio measurement configuration to the userequipment, wherein the radio measurement configuration is indicative forparameters to be applied by the user equipment for radio measurements,the radio measurement configuration comprising different parametersbeing assigned to different cell type characteristics, and a controlunit for controlling the radio measurements of the user equipment basedon the provided radio measurement configuration.
 13. A user equipmentbeing adapted to communicate with the base station as set forth in claim12 and being adapted to carry out radio measurements based on theprovided radio measurement configuration.
 14. A cellular network system,the cellular network system comprising a base station as set forth inclaim 12